INFO: RPC over HTTP deprecated in Office 365 on October 31, 2017

On Oct 31, 2017, RPC over HTTP will be deprecated in Exchange Online in favor of MAPI over HTTP, a modern protocol that was launched in May 2014.

This change affects you if you’re running Outlook 2007 because it won’t work with MAPI over HTTP. (The successor protocol to RPC over HTTP)

It also affects Outlook 2016, Outlook 2013, and Outlook 2010 users who aren’t running updated versions of the products that may still leverage RPC over HTTP instead of the current MAPI over HTTP standard.

Why MAPI over HTTP? MAPI over HTTP provides the following benefits:

Provides faster connection times to Exchange

Improves the connection resiliency when the network drops packets in transit

Provides the extensibility foundation for 3rd party identity providers

Removes the complexity of RPC over HTTP’s dependency on the legacy RPC technology

How do we address the sunsetting of RPC over HTTP? To continue email connectivity:

Outlook 2007 customers will have to update to a newer version of Outlook or use Outlook on the web.

Outlook 2016, Outlook 2013, and Outlook 2010 users must make sure that the latest cumulative update for the version of Office installed is applied.

Microsoft recommends customers keep their users updated to the most recent product update, as several MAPI over HTTP bugs have been fixed between since December 2015. Office 365 customers should review this how-to article which outlines the steps necessary to upgrade users to the latest version of Office.

Additionally, customers may need to ensure their Outlook clients are not using a registry key to block MAPI over HTTP. Details about this registry key can be found in this KB article on our support site.

Lastly, customers should ensure that they do not have any Outlook add-ins or 3rd party apps that rely on the RPC over HTTP protocol to connect to Office 365 data.

How can I confirm a client is enabled for MAPI over HTTP? By default, when a mailbox is created in or migrated to Exchange Online, it is enabled for MAPI. You can confirm/verify that your mailboxes are enabled for MAPI connections using the following command from a Remote EXO PowerShell session to your tenant:

This might come in handy if you find someone is connecting via RPC/HTTP instead of MAPI/HTTP.

Another way to check is to look at Outlook’s Connection status (for older versions of Outlook): How to Check Outlook’s connection status – Connecting RPC will show RPC/HTTP in the Protocol column, Connecting MAPI/HTTP will show HTTP in the Protocol column.

Does this deprecation affect Outlook for Mac, iOS, Android, Windows 10 Mobile or the web? No. This only applies to Outlook for Windows.

Does this deprecation in Office 365 affect customers using Exchange on-premises (Exchange 2007-2016)? No. Customers using RPC over HTTP to connect Outlook and Exchange on-premises can continue to do so. This only affects mailboxes in Exchange Online.

For official information about what steps to take, or for a greater explanation of why this is happening, go to: